Four senior ministers in the Abbott government have been assigned secret-service style protection amid an angry backlash over the federal budget, while a fifth minister is also receiving personal protection over specific threats.

The unprecedented ramp-up in security measures has seen Treasurer Joe Hockey, Foreign Minister Julie Bishop, Education Minister Christopher Pyne and junior Defence minister Stuart Robert assigned Close Personal Protection officers from the Federal Police in the month since the budget.

Immigration Minister Scott Morrison has also been assigned CPP teams in recent months, with his controversial portfolio said to be the reason to ramp-up protection, not the budget.

Government sources have admitted the extent of the protection measures required is unusual.

CPP teams are assigned full-time to protect Prime Minister Tony Abbott and the Israeli and US Ambassadors, while convention dictates that the deputy prime minister receives personal protection when the Prime Minister of the day is overseas.

However, in just the past month CPP has been assigned to provide the highest level of security to a slew of public events - many at universities:

❏ Ms Bishop was assigned a CPP team before a visit to Sydney University on May 16, three days after the budget.

The Foreign Minister was confronted and jostled by angry students, forcing her CPP team to intervene.

❏ Mr Hockey was accompanied on May 19 by a CPP team when he made an appearance on the ABC's Q&A, six days after the budget.

Mr Hockey also had a protection detail assigned to his residence in Canberra about the time of what has been a tough and unpopular budget.

❏ Mr Pyne's was assigned a CPP team for an appearance at Sydney University's St Johns College on May 22.

This was one of several occasions the Education Minister, who is driving controversial reforms, has needed protection from the elite unit.

❏ Mr Robert was assigned a CPP team for a visit to the Australian National University on May 29.

Federal police provide an assessment on ministers forward programs to assess whether there is a threat or a risk and whether further protection might be required.

Mr Pyne told the Nine Network on Friday that he and other ministers had been assigned protection by the federal police following the budget.

''When I visit university campuses the Australian Federal Police have made the assessment that it's wise for me to be accompanied by AFP officers and to do security checks in the places where I'm visiting,'' he said.

''That’s just part of the process of being in government really when you’re making major reforms and some of the students are taking the opportunity to protest.''

In the week after the budget, Mr Abbott was forced to cancel a visit to a Victorian university.

Former Labor immigration minister Chris Bowen had teams assigned to him on a regular basis in response to specific threats, like Mr Morrison.